Hi,
This patch fixes a bug in the GFS2 block allocation code. The problem
starts if a process already has a multi-block reservation, but for
some reason, another process disqualifies it from further allocations.
For example, the other process might set on the GFS2_RDF_ERROR bit.
The process holding the reservation jumps to label skip_rgrp, but
that label comes after the code that removes the reservation from the
tree. Therefore, the no longer usable reservation is not removed from
the rgrp's reservations tree; it's lost. Eventually, the lost reservation
causes the count of reserved blocks to get off, and eventually that
causes a BUG_ON(rs->rs_rbm.rgd->rd_reserved < rs->rs_free) to trigger.
This patch moves the call to after label skip_rgrp so that the
disqualified reservation is properly removed from the tree, thus keeping
the rgrp rd_reserved count sane.
Regards,
Bob Peterson
Red Hat File Systems
Signed-off-by: Bob Peterson <rpeterso redhat com>
---
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 711e835..ddcddce 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1949,15 +1949,16 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, const struct gfs2_alloc_parms *a
return 0;
}
- /* Drop reservation, if we couldn't use reserved rgrp */
- if (gfs2_rs_active(rs))
- gfs2_rs_deltree(rs);
check_rgrp:
/* Check for unlinked inodes which can be reclaimed */
if (rs->rs_rbm.rgd->rd_flags & GFS2_RDF_CHECK)
try_rgrp_unlink(rs->rs_rbm.rgd, &last_unlinked,
ip->i_no_addr);
skip_rgrp:
+ /* Drop reservation, if we couldn't use reserved rgrp */
+ if (gfs2_rs_active(rs))
+ gfs2_rs_deltree(rs);
+
/* Unlock rgrp if required */
if (!rg_locked)
gfs2_glock_dq_uninit(&rs->rs_rgd_gh);